A wireless device (e.g., a cellular phone or a smartphone) in a wireless communication system may transmit and receive data for two-way communication. The wireless device may include a transmitter for data transmission and a receiver for data reception. For data transmission, the transmitter may modulate a radio frequency (RF) carrier signal with data to generate a modulated RF signal, amplify the modulated RF signal to generate a transmit RF signal having the proper output power level, and then transmit the transmit RF signal via an antenna to a base station. For data reception, the receiver may obtain a received RF signal via the antenna and may amplify and process the received RF signal to recover data sent by the base station.
The wireless device may include one or more amplifiers to process analog signals. For example, amplifiers may provide a processing gain (e.g., voltage or current gain) for relatively low amplitude signals, isolation for relatively sensitive signals, increased current for driving signals into transmission lines, and signal amplification for transmitting signals through a communication medium.
Some amplifiers may provide more than adequate amounts of processing gain, but may also have some undesirable operating characteristics. For example, some amplifiers may be unstable at certain operating points (e.g., an output of the amplifier may oscillate or otherwise no longer correspond to an input of the amplifier at certain input/output levels). Amplifier instability may render the amplifier inoperable and/or unreliable.
Feedback techniques, such as negative feedback techniques, may be used to increase the stability of an amplifier design. While negative feedback techniques may increase stability, negative feedback may also adversely affect a frequency response and/or bandwidth of the amplifier.
Thus, there is a need to improve amplifier stability while reducing and/or limiting a negative impact on frequency response and/or bandwidth.